The University of Otago has said staff from the Proctor's office removed around 500 issues from stands, which it says was a mistake. Critic said around 1500 to 2000 copies had disappeared.

The issue is still available online where it has seen a surge in readership, and Trade Me expects to see interest in the listing skyrocket in the coming days.

"We think this is an excellent example of the Streisand effect - censoring this issue has made it much more newsworthy than it would have been initially," said Trade Me spokesperson Millie Silvester.

"We think a lot of Trade Me members will be keen to check out the auction and there are bound to be some collectors keen on getting their hands on a piece of student media history."

Photo credit: Trade Me

Critic is funded by students through the Otago University Students Association and operates independently from the university.

The menstruation issue was released on Monday and by Tuesday morning every stand on campus was uncharacteristically empty.

At first Critic suspected the copies had been removed as part of a prank or a protest, but later that day the university put out a press release saying the copies had been removed by Campus Watch staff.

Critic editor Joel MacManus said: "It was never our intention to offend with this cover, it was to grab attention and to do something different. The artist wrote that she designed it to suggest that people who bleed should be empowered, that they get on with life, almost wanted to normalise it in a way."

There was still some confusion over why the university had taken this step, and who was responsible.

"We wish they'd come to us first before taking it into their own hands and destroying all the copies," Mr MacManus told RadioLIVE.

"The subject matter was put forward by the Otago Women's+ Club and we feel expressed a number of really important viewpoints on important issues and uncovered a few very important stories."

The release of the issue coincides with the Women's+ Club's 'Period Week'.

In a statement on Wednesday morning, the university said it "made no decision to remove the editions of Critic from university stands".

"Because Critic staff had removed copies of the edition from the Dunedin Public Library and the Dunedin Public Hospital on Monday, as they are public places, staff in the Proctor's office believed that it should follow that copies also be removed from campus.

Critic staff removed copies from the hospital on request, and had left a box at the library for them to make their own decision about whether to put the issues out.

"Regrettably, they removed approximately 500 copies and disposed of them. No directions were given to Campus Watch from the university on this matter. This was a mistake and never intended as censorship," the university said in a statement.

An open letter signed by a number of former Critic editors has accused the University of Otago of censorship and asked it to apologise for removing and destroying the issues.